Book Information: Ring of Swords

From the publisher:For nearly fifty years, humanity has been in conflict with a spacefaring race of warlike humanoid aliens, the only advanced and intelligent race thus far encountered in the exploration of space. Humans hope to avoid interstellar war with this enigmatic race, and have set up the first diplomatic talks with them on an isolated and strategically unimportant planet.

Biological researcher Anna Perez has a grant to study the huge, jellyfishlike aliens who live in the seas on this far planet. As the talks begin, she learns that the alien diplomats have a translator, Nicholas Sanders, who to the astonishment of all is the first human turncoat.

So begins a story of deepening conflict, complicated by racial and sexual roles, attitudes towards aggression, and misunderstood customs haunted by the spectre of an unimaginable war, a complex tale of the future that confirms Eleanor Arnason's place among the leading SF writers of the decade.